1.Factors that block production and equipment specifications for preventing them

The factors that determine production volume are cycle time, operating hours, and operating rate. Since operating hours cannot be increased beyond 24 hours per day, productivity can be increased by improving cycle time and availability.

definition of cycle time and equipment specifications

Cycle time is the idea of how many seconds it takes to complete a unit of product.
Such as cycle time requirement for making one product every 10 seconds. If the same work cycle can be maintained throughout the day, the operating rate will be close to 100%, so you can expect to produce the expected number of products in cycle time. (*For example, in this case, it's 360 units per hour.)

In reality, however, this is not the case. This is because there are various obstacles that prevent the product from being produced within the cycle time.

cycle time and operating rate

Looking at cycle time in a little more detail, cycle time is the sum of the time that the equipment is operating and the time that the workers are working. If each cycle does not include human operation, the equipment operation time is the cycle time as it is. In the case of plastic molding and die-casting machines, the equipment operation time becomes the cycle time because they operate continuously on an automatic cycle.

In the case of stand-alone assembly equipment, product loading and unloading is often done by humans, and the cycle time is calculated by including product loading and unloading time. If the workers are slow or material flow from the previous process is poor, the cycle time will be longer as a result.

At this time, the equipment is just waiting for the next operation to start. In other words, the equipment is on standby. The idea of not letting the equipment run idle and allowing it to operate continuously is an ingenious way to increase productivity.

2.Equipment specifications and concepts for operating the equipment at full efficiency

The following are some of the factors that prevent equipment operation and their solutions.

Separate loading and unloading

Following mechanism is often seen in single machines. In the most case of product pull-in type equipment, the loading and unloading points are the same. While this method is advantageous in terms of product positioning, it is not advantageous in terms of operating rate. The reason for this is that equipment operation is always stopped during product unloading and loading.

Separate loading and unloading and load the next product before previous product is unloaded. Then, if you program the machine to automatically start the next cycle at the end of previous cycle, you can run the equipment without stopping. In this case, human operation time will be zero.

Provide multiple product storage areas at the product unloading point

Next, let's look at the discharge point. You can imagine an injection molding machine. The molding machine has a tray at discharge point. And product is automatically stored there. The assembly equipment does not allow the product to be dropped. If it is possible to have some buffer at the discharge point, the equipment does not have to wait for worker to remove the product.

Most of the time, workers are working on multiple tasks. They may be too busy with other tasks to get the product out in a certain cycle. Even in such cases, for example, if a conveyor is installed in the discharge section and designed to store the material, the equipment can be operated continuously. This depends on the cycle of the workers.

If they can afford it, you won't have to think about this. But if they are concurrently working with a time-consuming process, the equipment could absorb some of the loss.

Automatic ejection when NG occurs

The occurrence of NG is also a factor that worsens the operating rate. Whenever NG is detected and release operation is required, the product does not flow in the expected cycle. Especially when it comes to automated machines, this pause time can be a big loss.

With the same concept as above, if the system is controlled so that NG can be automatically discharged and returned to the normal cycle even if NG is generated, there is no need for workers to release and restart the equipment.

In addition, if the NG products can be discharged without stopping the automatic cycle, the operator can remove the NG products at his convenient time.

Stop by area sensor

Cycle stops caused by area sensors can also reduce availability.
It's a safety device, so it can't be cheated. but it's not smart if the equipment shuts down just because the area sensor is accidentally shielded. For example, if the area sensor is shielded during the equipment cycle, the equipment can be stopped only temporarily, and when the shielding is released, the cycle operation can be resumed from the middle of the operation, avoiding the need to stop the equipment and repeat from the beginning each time.

3.Equipment specifications that do not stop the equipment

The above are some of the ways to keep the equipment operating rate. It's just a small idea, but if you think about it over a long period of time, that will make a big difference. These specifications need to be included in the equipment specification stage. Once the equipment is completed, the hurdle of changing the mechanism and control becomes high.

In the case of stand-alone machine, it also has to do with operating rate and whether or not it is a bottleneck process. If the process is not a bottleneck, even if there is a slight operating loss in that process, it is possible to recover the loss if we have enough parts in process.
On the other hand, in the case of automated equipment, if you don't review the above-mentioned ideas of keeping the operating rate, you may have a hard time after installation. Engineers should consider this and include it in the specifications for new equipment.


RELATED) The concept and benefits of standardizing mass production equipment
RELATED) How to write equipment specifications